使用OpenLayer加载百度地图（无偏移）

本文使用OpenLayers最新版本V5.3.0演示：如何使用OpenLayer完美无偏移加载百度离线瓦片地图。OpenLayers 5.3.0下载地址为：https://github.com/openlayers/openlayers/releases/download/v5.3.0/v5.3.0-dist.zip 。

 

 

使用OpenLayer加载百度地图离线瓦片地图

任意新建空目录命名为geTileMap；解压v5.3.0-dist.zip并复制其中ol.js、ol.css文件至geTileMap目录；geTileMap目录下新建tiles空目录，并复制之前下载的12~18级演示瓦片至tiles目录；最后新建名为index.html文件。

完成上述操作后，目录结构如下：

 

打开index.html输入如下源码：

 

bd09.js

var MCBAND = [12890594.86, 8362377.87, 5591021, 3481989.83,
	1678043.12, 0
];
var LLBAND = [75, 60, 45, 30, 15, 0];
var MC2LL = [
	[1.410526172116255e-8, 0.00000898305509648872, -1.9939833816331, 200.9824383106796, -187.2403703815547, 91.6087516669843, -23.38765649603339, 2.57121317296198, -0.03801003308653, 17337981.2],
	[-7.435856389565537e-9, 0.000008983055097726239, -0.78625201886289, 96.32687599759846, -1.85204757529826, -59.36935905485877,
		47.40033549296737, -16.50741931063887,
		2.28786674699375, 10260144.86
	],
	[-3.030883460898826e-8, 0.00000898305509983578,
		0.30071316287616, 59.74293618442277,
		7.357984074871, -25.38371002664745,
		13.45380521110908, -3.29883767235584,
		0.32710905363475, 6856817.37
	],
	[-1.981981304930552e-8, 0.000008983055099779535,
		0.03278182852591, 40.31678527705744,
		0.65659298677277, -4.44255534477492,
		0.85341911805263, 0.12923347998204, -0.04625736007561, 4482777.06
	],
	[3.09191371068437e-9, 0.000008983055096812155,
		0.00006995724062, 23.10934304144901, -0.00023663490511, -0.6321817810242, -0.00663494467273, 0.03430082397953, -0.00466043876332, 2555164.4
	],
	[2.890871144776878e-9, 0.000008983055095805407, -3.068298e-8, 7.47137025468032, -0.00000353937994, -0.02145144861037, -0.00001234426596, 0.00010322952773, -0.00000323890364, 826088.5]
];

var LL2MC = [
	[-0.0015702102444, 111320.7020616939,
		1704480524535203, -10338987376042340,
		26112667856603880, -35149669176653700,
		26595700718403920, -10725012454188240,
		1800819912950474, 82.5
	],
	[0.0008277824516172526, 111320.7020463578,
		647795574.6671607, -4082003173.641316,
		10774905663.51142, -15171875531.51559,
		12053065338.62167, -5124939663.577472,
		913311935.9512032, 67.5
	],
	[0.00337398766765, 111320.7020202162,
		4481351.045890365, -23393751.19931662,
		79682215.47186455, -115964993.2797253,
		97236711.15602145, -43661946.33752821,
		8477230.501135234, 52.5
	],
	[0.00220636496208, 111320.7020209128,
		51751.86112841131, 3796837.749470245,
		992013.7397791013, -1221952.21711287,
		1340652.697009075, -620943.6990984312,
		144416.9293806241, 37.5
	],
	[-0.0003441963504368392, 111320.7020576856,
		278.2353980772752, 2485758.690035394,
		6070.750963243378, 54821.18345352118,
		9540.606633304236, -2710.55326746645,
		1405.483844121726, 22.5
	],
	[-0.0003218135878613132, 111320.7020701615,
		0.00369383431289, 823725.6402795718,
		0.46104986909093, 2351.343141331292,
		1.58060784298199, 8.77738589078284,
		0.37238884252424, 7.45
	]
];

function lngLatToMercator(T) {
	var c = new cd(T[0], T[1]);
	var r = convertLL2MC(c);
	return [r.lng, r.lat];
}

function mercatorToLngLat(T) {
	var c = new cd(T[0], T[1]);
	var r = convertMC2LL(c);
	return [r.lng, r.lat];
}

function convertLL2MC(T) {
	var cL, cN;
	T.lng = getLoop(T.lng, -180, 180);
	T.lat = getRange(T.lat, -74, 74);
	cL = new cd(T.lng, T.lat);
	for(var cM = 0; cM < LLBAND.length; cM++) {
		if(cL.lat >= LLBAND[cM]) {
			cN = LL2MC[cM];
			break
		}
	}
	if(!cN) {
		for(var cM = LLBAND.length - 1; cM >= 0; cM--) {
			if(cL.lat <= -LLBAND[cM]) {
				cN = LL2MC[cM];
				break
			}
		}
	}
	var cO = convertor(T, cN);
	var T = new cd(cO.lng.toFixed(2), cO.lat.toFixed(2));
	return T
}

function convertMC2LL(cL) {
	var cM, cO;
	cM = new cd(Math.abs(cL.lng), Math.abs(cL.lat));
	for(var cN = 0; cN < MCBAND.length; cN++) {
		if(cM.lat >= MCBAND[cN]) {
			cO = MC2LL[cN];
			break
		}
	}
	var T = convertor(cL, cO);
	var cL = new cd(T.lng.toFixed(6), T.lat.toFixed(6));
	return cL
}

function getRange(cM, cL, T) {
	if(cL != null) {
		cM = Math.max(cM, cL)
	}
	if(T != null) {
		cM = Math.min(cM, T)
	}
	return cM
}

function getLoop(cM, cL, T) {
	while(cM > T) {
		cM -= T - cL
	}
	while(cM < cL) {
		cM += T - cL
	}
	return cM
}

function convertor(cM, cN) {
	if(!cM || !cN) {
		return
	}
	var T = cN[0] + cN[1] * Math.abs(cM.lng);
	var cL = Math.abs(cM.lat) / cN[9];
	var cO = cN[2] + cN[3] * cL + cN[4] * cL * cL + cN[5] * cL *
		cL * cL + cN[6] * cL * cL * cL * cL + cN[7] * cL *
		cL * cL * cL * cL + cN[8] * cL * cL * cL * cL *
		cL * cL;
	T *= (cM.lng < 0 ? -1 : 1);
	cO *= (cM.lat < 0 ? -1 : 1);
	return new cd(T, cO)
}

function cd(T, cL) {
	if(isNaN(T)) {
		T = bV(T);
		T = isNaN(T) ? 0 : T
	}
	if(b3(T)) {
		T = parseFloat(T)
	}
	if(isNaN(cL)) {
		cL = bV(cL);
		cL = isNaN(cL) ? 0 : cL
	}
	if(b3(cL)) {
		cL = parseFloat(cL)
	}
	this.lng = T;
	this.lat = cL
}
cd.isInRange = function(T) {
	return T && T.lng <= 180 && T.lng >= -180 && T.lat <= 74 &&
		T.lat >= -74
};
cd.prototype.equals = function(T) {
	return T && lat == T.lat && lng == T.lng
};

function bV(cN) {
	var cL = "";
	var cU, cS, cQ = "";
	var cT, cR, cP, cO = "";
	var cM = 0;
	var T = /[^A-Za-z0-9\+\/\=]/g;
	if(!cN || T.exec(cN)) {
		return cN
	}
	cN = cN.replace(/[^A-Za-z0-9\+\/\=]/g, "");
	do {
		cT = cf.indexOf(cN.charAt(cM++));
		cR = cf.indexOf(cN.charAt(cM++));
		cP = cf.indexOf(cN.charAt(cM++));
		cO = cf.indexOf(cN.charAt(cM++));
		cU = (cT << 2) | (cR >> 4);
		cS = ((cR & 15) << 4) | (cP >> 2);
		cQ = ((cP & 3) << 6) | cO;
		cL = cL + String.fromCharCode(cU);
		if(cP != 64) {
			cL = cL + String.fromCharCode(cS)
		}
		if(cO != 64) {
			cL = cL + String.fromCharCode(cQ)
		}
		cU = cS = cQ = "";
		cT = cR = cP = cO = ""
	} while (cM < cN.length);
	return cL
}

function b3(T) {
	return typeof T == "string"
}

保存后浏览器中运行演示OpenLayer完美无偏移加载百度离线瓦片地图效果。下图为Chrome中运行实例截图和局部放大后截图：

 

 

如需要定位的话，添加以下方法：

function searchPoint(_point) {
        _point = tobdMap(_point.split(","));//如果传入的是火星坐标系的话，要转成百度坐标系
        var point = new ol.Feature({geometry:
        new ol.geom.Point(ol.proj.fromLonLat(_point, 'BD:09'))})// 将经纬度转成BD:09投影，此投影需引入bd09.js
        point.setStyle(new ol.style.Style({
                image:new ol.style.Icon({
                anchor: [0.5, 1],
        src:
        basePath + "/img/localpoint.png"
        })

    }));

        pointSource.clear();
        pointSource.addFeature(point);
        map.setView(new ol.View({
                center:ol.proj.transform(_point, 'EPSG:4326', 'EPSG:3857'),
                zoom:8,
                maxZoom:19
    }));
 };

//火星坐标系转百度坐标系
function tobdMap(coordinate) {
	    let x_pi = 3.14159265358979324 * 3000.0 / 180.0;
	    let x = coordinate[0];
	    let y =  coordinate[1];
	    let z = Math.sqrt(x * x + y * y) + 0.00002 * Math.sin(y * x_pi);
	    let theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * x_pi);
	    let lngs = z * Math.cos(theta) + 0.0065;
	    let lats = z * Math.sin(theta) + 0.006;
	    let zb=[];
	    zb[0]=lngs;
	    zb[1]=lats;
	    return zb;
	 }